Process of producing aluminum fluorid.



DAvID H. CHILDS, or ALFRED, new YORK.

PROCESS or PRODUCING ALUMINUM rLUoItID.

No Drawing. Application filed June 6, 1908, Serial No.

To all whom it may concern v Be it known that I, DAVID H. GrIILDs, a'citizen of the United States, residing at Alfred, in the county of Allegany' andState of New York, have invented a new and useful Improvement in Processes of Produc ing Aluminum Fluorid, of which the following is a specification.

Ihis invention relates to theprocess of producing aluminum fiuorid in the manufacture of aluminum oxid.

Aluminum fluorid, when calcined in the presence of water or water vapor, produces aluminum oxid asa solid and hydrofluoric acid gas. The aluminum oxid so produced is practically pure and very desirable in the manufacture of pure aluminum, but this process of obtaining it has heretofore failed to be commercially successful, owing to the difficulty and expense of producing alumi- The object of this invention is to" provide a process whereby aluminum fluorid may be cheaply and economically produced.

In practising this invention, hydrofluoric acid gas or some other volatile compound of fluorin, for example, silicon fluorid, as explained below, is caused to pass through a preferably kaolin, moist by a steady flow of which is kept formwater. The water takes upthe gas,

ingea dilute solution of hydrofluoric acid which attacks the kaolin or other compound in the form of crystals.

of aluminum, combining with the aluminum to aluminum fluorid which is dissolved in the water. The hydrofluoric acid being taken from the water in forming aluminum fluorid, leaves thewater free. to, take up more acid from the gas, which in turn acts upon the remaining aluminum of the com pound, so that eventually a strong solution of aluminum fluorid is produced. This solution is drawn oil and if acid is neutralized by the addition of more kaolin or other compound of aluminum, the acid combining with the aluminum as before to aluminum fluorid, and the iron and silica of the compound being precipitated. The solution is then filtered and evaporated, the aluminum fluorid remaining The aluminum fluorid can then be calcined to produce aluminum oxid and the process can be re peated with the hydrofluoric acid gas which passes off in thecalcining process.

Specification of Letters Patent.

Patented Aug. 20 1912.

437,039. Renewed June 4, 1912. Serial No. 701,653.

This process is also available in connection with the process of producing aluminum oxid from aluminum silicates which is described and claimed in a co-pending ap: plication for patent thereon filed by me August 15, 1910, Serial No. 577,280 in which process an aluminum silicate is.m1xed with aluminum fiuorid and heated suiliciently to cause the fluorin to react upon the silica, producing a. volatile compound of fluorin and silicon and leaving aluminum oxid The silicon fiuorid can then be passed through a compound of aluminum kept moist by a steady flow of water,in the manner above described, and will combine with the water, forming hydrated silicon oxid, which will be precipitated, and a dilute solution of hydrofluoric acid or hydrofluosilicic acid or both. These reactions may be expressed by the following equations:

SiF,+4l -l O: SlO ,2H Oj+4;HF. 2SiF l-411 0 H, SiF-l- SiO ,2l-l O+2H-F. The hydrofluoric acid and the hydrofluosilicic acidvso formed will attack the aluminum compound and produce aluminum fluorid in the manner above set forth. If the aluminum compound is kaolin (Al O ,2 SiO the reactions may be expressed by the following equations:

I claim as my invention:

1. The process of producing aluminum fluorid from aluminum compounds which consists in causing a volatile compound containing fluorin to pass through a mass of a compoundof aluminum which is kept moist by a constant supply of water, the water taking up the volatile fluorin com-, pound and forming a solution which attacks the aluminum compound producing aluminum fluorid and leaving the water free to absorb a further quantity of said volatile fluorin compound, thereby continuing the formation of the solution for attacking the aluminum compound, "substantially as set forth.

2.- The process of producing aluminum fiuorid from aluminum compounds which consists in causing hydrofluoric acid gas to pass through a mass of a compound of 10 of said gas,

aluminum which is kept ,moist by a constant supply of Water, the Water taking up the'gas and'forming a solution of hydrofluoric acid which attacks the aluminum compound producing aluminum fiuorid which is dissolved in the Water, the hydrofluoric acid being taken from the solution in forming the valuminum fluorid, leaving the Water free to absorb a further quantity thereby continuing the formation of a solution of hydrofluoric acid which further attacks the aluminum compound until the aluminum has been separated therefrom, substantially as set forth Witness my hand, this first day of June, 15

,D AVID H. CHILDS. Witnesses W. H. GRANDALL, E. E. HAMILTON. 

